Marine Geology 352 (2014) 426–450 Contents lists available at ScienceDirect Marine Geology journal homepage: www.elsevier.com/locate/margeo Establishing a new era of submarine volcanic observatories: Cabling Axial Seamount and the Endeavour Segment of the Juan de Fuca Ridge Deborah S. Kelley a,⁎,JohnR.Delaneya, S. Kim Juniper b a University of Washington, School of Oceanography, Seattle, WA 98195, United States b University of Victoria, Ocean Networks Canada, Victoria, BC V8W 2Y2, Canada article info abstract Article history: At least 70% of the volcanism on Earth occurs along the 65,000 km network of mid-ocean ridge (MOR) spreading Received 10 July 2013 centers. Within these dynamic environments, the highest fluxes of heat, chemicals, and biological material from the Received in revised form 4 March 2014 lithosphere to the hydrosphere occur during volcanic eruptions. However, because underwater volcanoes are dif- Accepted 6 March 2014 ficult and expensive to access, researchers are rarely, if ever, in the right place at the right time to characterize these Available online 20 March 2014 events. Therefore, our knowledge is limited about the linkages among hydrothermal, chemical and biological fl fi Keywords: processes during sea oor formation and crustal evolution. To make signi cant advancements in understanding fi submarine volcanoes the evolution of MOR environments, the United States and Canada have invested in the rst plate-scale submarine hydrothermal vents cabled observatory linked through the global Internet. Spanning the Juan de Fuca tectonic plate, these two Juan de Fuca Ridge networks include N1700 km of cable and 14 subsea terminals that provide 8–10 kW power and 10 Gbs commu- Endeavour Segment nications to hundreds of instruments on the seafloor and throughout the overlying water column — resulting in a Axial Seamount 24/7/365 presence in the oceans. Data and imagery are available in real- to near-real time. cabled observatories The initial experimental sites for monitoring volcanic processes include the MOR volcanoes called Axial Seamount and the Endeavour Segment that are located on the Juan de Fuca Ridge. Axial, a hot-spot influenced seamount, is the most robust volcano along the ridge rising nearly 1400 m above the surrounding seafloor and it has erupted twice in the last 15 years. In contrast, the Endeavour Segment is characterized by more subdued topography with a well defined axial rift and it hosts one of the most intensely venting hydrothermal systems known. A non-eruptive spreading event lasting 6 years was documented at Endeavour between 1999 and 2005. Hydrothermal venting intensity, chemistry, and temperature, as well as associated biological communities at both sites were significantly perturbed by the magmatic and intrusive events. This paper presents the simi- larities and differences between the Axial and Endeavour volcanic systems and identifies reasons why they are ideal candidates for comparative studies. The U.S. has made a 25-year commitment for sustained observations using the cabled infrastructure. The highly expandable nature of submarine optical networking will allow for the future addition of novel experiments that utilize ever evolving advancements in computer sciences, robotics, genomics and sensor miniaturization. Comprehensive modeling of the myriad processes involved will continue to assimilate and integrate growing databases yielding a new understanding of integrated processes that create the seafloor in the global ocean basins. Published by Elsevier B.V. 1. Transforming studies of volcanoes, hot springs, and life spaced oases on an otherwise barren seafloor, in the past three decades the discovery rate of vent sites has dramatically increased in response to For four billion years submarine volcanism has impacted the global maturation of search strategies and improved detection techniques: oceans, driving hot spring systems that not only influence the chemistry more than 300 vent sites have now been documented with evidence of the ocean, but which also support some of the most novel organisms of many more in the global oceans (Fig. 1). on Earth (Davis and Elderfield, 2004; Wilcock et al., 2004). Approxi- On-going discoveries about these remarkable environments contin- mately 70% of the volcanism on the planet occurs beneath the ocean's ue to astound us, from the chemical and physical nature of black surface, with much of the activity focused along the 65,000 km-long smokers and hydrothermally active fissure systems, to the multitude mid-ocean ridge (MOR) spreading system. Although, the associated hy- of highly-adapted life forms thriving within these extreme environ- drothermal vent ecosystems were initially viewed as isolated, widely- ments. Striking examples include the discovery of the 350 °C black smoker ‘Godzilla’ on the Endeavour Segment of the Juan de Fuca ⁎ Corresponding author. Ridge, which in 1995 stood as high as a 15-story building, towering http://dx.doi.org/10.1016/j.margeo.2014.03.010 0025-3227/Published by Elsevier B.V. D.S. Kelley et al. / Marine Geology 352 (2014) 426–450 427 Fig. 1. Global distribution of hydrothermal vents based on the InterRidge vent database (http://www.interridge.org/Irvents). Image produced by the Center for Environmental Visualization, University of Washington. over the surrounding volcanic terrain (Robigou et al., 1993). In 1999, sensors, and samplers that are in the right place at the right time to cap- one of the highest temperature organisms on Earth, capable of surviving ture the events/processes of interest. Distributed sensor networks in at temperatures 121 °C, was cultured from 1-year old black smoker ma- terrestrial environments, which provide real-time documentation terial recovered from the Endeavour (Kashefi and Lovley, 2003). about the environment and human activities are now widespread and In 2000, a completely different type of hydrothermal system was seren- accessible to a global audience via the Internet. However, similar capa- dipitously discovered on the Mid-Atlantic Ridge called the Lost City bilities in the oceans are extremely rare, leaving many of the significant Hydrothermal Field, hosting actively venting limestone chimneys that seafloor processes poorly characterized, particularly in both the time rise 60 m above the seafloor (Kelley et al., 2001a, 2005). Equally surpris- domain and at the required spatial scales. ing, in 2004 and 2010, shallow volcanic calderas in the Mariana arc and The major volcanic and tectonic processes that create the oceanic volcanoes in Lau Basin were discovered hosting pools of molten sulfur crust and modulate heat, chemical, and biological fluxes through the (Embley et al., 2006; Lupton et al., 2006) and explosive lava bubbles seafloor are inherently episodic on decadal timescales, but they are (Resing et al., 2011). Perhaps the most far-reaching of these discoveries, also punctuated by short-lived and frequent events. For example, however, is that life itself may have originated within these dynamic water column analyses above recently erupted submarine volcanoes systems in which geological, chemical, and biological processes are inti- show that significant heat, chemicals, and biological material are ejected mately linked (Baross and Hoffman, 1985; Martin et al., 2008; Langmuir into the overlying ocean during the formation of megaplumes and and Broecker, 2012). following eruptive events (Embley et al., 1991; Haymon et al., 1991; Although significant progress has been made in understanding Baker et al., 1995; Lupton, 1995; Delaney et al., 1998; Kelley et al., process linkages in these dynamic environments, further scientificad- 1998; Lupton et al., 1999; Lilley et al., 2003; Baker et al., 2004; Meyer vances are increasingly dependent on our ability to collect long-term, et al., 2013). The megaplumes are characterized by anomalous heat- high-frequency observations using diverse networks of platforms, helium content and are enriched in hydrogen and methane (Kelley et 428 D.S. Kelley et al. / Marine Geology 352 (2014) 426–450 al., 1998). They also have elevated manganese and iron concentrations submarine hydrothermal systems (Gold, 1992; Delaney et al., 1998; with respect to ocean background water (Lupton, 1995; Murton et al., Wilcock, 2004; Huber et al., 2007). 2006; Baker et al., 2012). The buoyant plumes can rise a thousand me- In 1987, it was recognized that while expedition-based exploration ters or more above the surrounding seafloor, they can be 20 km across, and study of these dynamic systems would always be important, the and 70 km in length (Baker et al., 1987; Lupton, 1995; Lupton et al., only way to capture these high impact events would be to maintain 1999; Murton et al., 2006). It is likely that they form extremely rapidly, long-term, real-time monitoring and response capabilities at a number perhaps on the order of a few hours (Lavelle, 1995). The rising fluids of sites with high probability for magmatic and/or tectonic activity. contain novel subseafloor thermophilic microorganisms, injected into From this recognition, the concept of installing high-power and high- the overlying ocean as crustal fluids are flushed from depth (Delaney bandwidth underwater cabled observatories emerged. These first con- et al., 1998; Summit and Baross, 1998, 2001; Meyer et al., 2013). Subse- ceptual arrays focused on highly energetic Earth and ocean processes quent to formation, the megaplumes are wafted away from the ridge operating in shallow coastal waters off of Washington, Oregon, and Brit- axis by ocean currents.